Azo dyestuffs



Patented June 1, 1937 FFIE AZO DYESTUFFS poration of Delaware NoDrawing. Application February 3, 1936, Serial No. 62,168. In GermanyFebruary 22,

Claims.

The present invention relates to new azo dyestufis.

A process for the manufacture and production of new azo dyestuiis isdescribed in our copending application Ser. No. 9349, filed March lth,1935, according to which diam-compounds of ortho-aminophenols which arefree from sulphonic or carboxylic acid groups and which contain one ormore nitro groups of which one is in para-position to the amino groupand containing, if desired, any further substituents are coupled withsuch N-hydroxyalkylated derivatlves of meta-toluidine in which thenitrogen atom is a tertiary one, i. e. which bears a furtherhydroxyalkyl group or an alkyl group.

We have now found that especially valuable dyestufis are obtained bycoupling diazo compounds of 3-halogen 5 nitro 2 aminophenols withN-hydroxyalkylated derivatives of metatoluidine in which the nitrogenatom is a tertiary one, i. e. which bears a further hydroxyalkyl groupor an alkyl group.

The dyestufis obtainable according to this invention are eminentlysuitable for dyeing cellulose esters and ethers. They yield valuablebluish dyeings thereon which are of a purity and clarity which havenever hitherto been obtained in the corresponding shades of color. Thedyeings have good fastness to light and washing and are capable of beingdischarged togive a pure white color. The dyestufis may also be used forcoloring resin and nitrocellulose lacquers.

The following example will further illustrate how this invention may becarried out in practice, but the invention is not restricted to thisexample. The parts are by weight.

Example 300 parts of a 23 per cent solution of sodium nitrite are addedto a solution of 233 parts of 3- brom -5- nitro -2- aminophenol(obtainable by treating a suspension of 5-nitro2-aminophenol in glacialacetic acid with the calculated amount of bromine at about C.) in amixture of 120 parts of 35 per cent caustic soda solution and 5000 partsof water .and the mixture is poured into 800 parts of 18 per centhydrochloric acid. The reddish yellow suspension of the diazo compoundthus obtained is then added to a solution of 210 parts ofN-di-hydroxyethyl-meta-toluidine in 240 parts of 18 per centhydrochloric acid and 2000 parts of water. The coupling is completed bythe addition of 600 parts of sodium acetate. The dyestuff is thenfiltered off by suction and washed. It yields on acetate artificial silkbrilliant red-violet dyeings which have a good fastness to light and arecapable of being discharged in pure white shades.

A very similar dyestufi is obtained by using the diazo compound of3-chlor-5-nitro-2-aminophenol.

If 220 parts of N-hydroxyethyl-N-butyl-metatoluidine be employed insteadof N-di-hydroxyethyl-meta-toluidine, a dyestufi is obtained which yieldsblue-violet dyeings having similar very good properties on acetateartificial sillr.

What we claim is:

1. A20 dyestuffs produced by coupling the diazo compound of a3-halogen-5-nitro-2-aminophenol with an N-hydroxylalkylated derivativeof meta-toluidine in which the nitrogen atom is a tertiary one.

2. Azo dyestuffs produced by coupling the diazo compound of a3-halogen-5-nitro-2-aminophenol with an N-di-hydroxyalkylated derivativeof meta-toluidine.

3. Azo dyestuffs corresponding to the formula I KU O2 Br CiHc N omomoHH:

KARL HOLZACH. BERND V. BOCK.

